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T T Sun

Publications and source records attributed to T T Sun.

At least 91 records · Page 5Linked to original sources
PubMed1993

Molecular cloning of a 47 kDa tissue-specific and differentiation-dependent urothelial cell surface glycoprotein.

Despite the fact that bladder epithelium has many interesting biological features and is a frequent site of carcinoma formation, relatively little is known about its biochemical differentiation. We have shown recently that a 47 kDa glycoprotein, uroplakin III (UPIII), in conjunction with uroplakins I (27 kDa) and II (15 kDa), forms the asymmetric unit membrane (AUM)--a highly specialized biomembrane characteristic of the apical surface of bladder epithelium. Deglycosylation and cDNA sequencing revealed that UPIII contains up to 20 kDa of N-linked sugars attached to a core protein of 28.9 kDa. The presence of an N-terminal signal peptide sequence and a single transmembrane domain located near the C terminus, plus the N-terminal location of all the potential N-glycosylation sites, points to a type I (N-exo/C-cyto) configuration. Thus the mass of the extracellular domain (20 kDa plus up to 20 kDa of sugar) of UPIII greatly exceeds that of its intracellular domain (5 kDa). Such an asymmetrical mass distribution, a feature shared by the other two major uroplakins, provides a molecular explanation as to why the luminal leaflet of AUM is almost twice as thick as the cytoplasmic one. The fact that of the three major proteins of AUM only UPIII has a significant cytoplasmic domain suggests that this molecule may play an important role in AUM-cytoskeleton interaction in terminally differentiated urothelial cells.

Amino Acid Sequence↗
PubMed1993

Cornea-specific expression of K12 keratin during mouse development.

The full-length cDNA of mouse K12 keratin was characterized by sequencing overlapping cDNA clones isolated from a mouse cornea cDNA library. Using Northern blot hybridization, the radio-labeled cDNA hybridized to a 1.9 kb mRNA from adult cornea, but not from other mouse tissues including snout, esophagus, tongue, and skin. During mouse development, corneas do not express K12 mRNA until 4 days postnatal when the epithelium begins to stratify as judged by Northern blot and in situ hybridization. In situ hybridization with 3H-labeled cDNA probe and immunohistochemical studies with antibodies against a synthetic oligo-peptide deduced from rabbit K12 cDNA demonstrate that this mouse K12 keratin is expressed in all cell layers of adult corneal epithelium, and the suprabasal layers, but not the basal layer of the limbal epithelium. Epidermal growth factor (EGF) has been shown to promote epithelium stratification of cultured chicken and human corneas in vitro. To examine whether EGF can promote K12 expression, EGF was administered to neonatal mice. The results indicate that EGF retards K12 expression by corneal epithelial cells, even though it promotes corneal epithelial stratification during mouse development. Taken together, our results demonstrate that the expression of K12 keratin is cornea-specific, differentiation-dependent, and developmentally regulated.

Amino Acid Sequence↗
PubMed1993

[Uroplakin III, a specific membrane protein of urothelial umbrella cells, as a histological markers for metastatic transitional cell carcinomas].

We have investigated, by immunohistochemical staining of various paraffin-embedded carcinoma sections, the tissue-specific expression of uroplakin III--a recently characterized constituent glycoprotein (47 kD) of the asymmetrical unit membrane which forms plaques on apical surface of urothelial umbrella cells. The apical membrane pattern of normal urothelial umbrella cells was in part maintained in papillary transitional cell carcinomas (TCCs). In addition, in both papillary and invasive TCCs, variously sized lumina exhibited positive membrane staining of uroplakin III. In some cases, basal cell membrane staining was seen. Positive reactions (which sometimes were very focal) were noted in 16/18 papillary non-invasive TCCs (89%), 21/37 invasive TCCs (57%) and 12/15 TCC metastases (80%). Non-TCC carcinomas of different origin (n = 63) were consistently negative. These results show that uroplakin III may serve as a useful marker for TCCs, revealing specific urothelial differentiation features to be expressed in such tumors even after metastasis. This marker, while of only intermediate sensitivity, is highly specific, thus opening interesting histodiagnostic possibilities in the case of unclear carcinoma metastases.

Biomarkers, Tumor↗
PubMed1993

In vitro growth and differentiation of rabbit bulbar, fornix, and palpebral conjunctival epithelia. Implications on conjunctival epithelial transdifferentiation and stem cells.

PURPOSE: The anterior surface of the eye is covered by several physically contiguous but histologically distinguishable epithelial overlying the cornea, limbus, bulbar conjunctiva, fornix conjunctiva, and palpebral conjunctiva. It is important to determine whether the different phenotypes of these epithelia are the result of intrinsic divergence, extrinsic modulation, or a combination of both. Based on keratin expression and cell kinetic criteria, the authors previously suggested that corneal epithelial stem cells may actually reside in the limbal basal layer. METHODS: In this article, the relationship between the corneal-limbal epithelial cells and conjunctival epithelial cells was analyzed by comparing their growth and differentiation properties in an identical cell culture environment. RESULTS: Using Dispase instead of trypsin to dissociate the cells, the authors were able to grow all five rabbit ocular surface epithelia in the presence of 3T3 feeder cells. They found that corneal and limbal cells synthesize identical keratins, including large amounts of the K3 and K12 markers of corneal-type differentiation. By contrast, all three conjunctival epithelia shared another keratin pattern, with large amounts of simple epithelial keratins but only minute amounts of K3/K12 keratins. CONCLUSIONS: This observation, coupled with previous findings that the "transdifferentiation" of conjunctival epithelial cells to corneal epithelium appears to be both incomplete and reversible, provides strong evidence that (1) the limbal-corneal epithelial cells form a lineage distinct from the conjunctival lineage and (2) conjunctival transdifferentiation actually represents a process of environmental modulation. In addition, of the three types of conjunctival epithelial cells, fornix cells were found to have a much greater proliferative potential than bulbar and palpebral cells. This observation, coupled with recent finding that fornix is enriched in slow-cycling (label-retaining) cells, raises the possibility that conjunctival epithelial stem cells may preferentially reside in the fornix.

Animals↗
PubMed1992

Characterization of a keratinocyte-specific extracellular epitope of desmoglein. Implications for desmoglein heterogeneity and function.

Despite the presumed importance of desmoglein, a 160-kDa glycoprotein, in desmosome formation and its possible involvement in certain blistering skin diseases, the precise location and function of this protein have not yet been firmly established. We describe here the characterization of a new monoclonal antibody, AE23, against an extracellular epitope of desmoglein. Both the AE23 epitope and another epitope, defined by the previously characterized DG3.4 antibody, reside on a 160-kDa human epidermal desmoglein as evidenced by their identical solubility profile, their coexistence in a 130-kDa desmoglein degradative product, their coadsorption by an AE23 immunoaffinity column, and the identical changes in the two antigens' electrophoretic mobility after air oxidation and deglycosylation. The AE23 epitope is resistant to various endoglycosidases, suggesting that sugar moieties are not involved. Characterization of several proteolytic fragments of this epidermal desmoglein enabled us to map the DG3.4 epitope to a 96-kDa intracellular domain and the AE23 epitope to an extracellular domain flanked by the plasma membrane and the distal N-glycosylation site(s). However, these two epitopes do not always coexist on the same desmoglein molecule. For example, tissue surveys showed that although the DG3.4 epitope is present in the desmogleins of all epithelial cell types, the AE23 epitope is limited to normal keratinocytes. Moreover, electron microscopic localization data indicate that whereas the DG3.4 epitope is detected in the submembranous plaques of desmosomes, the AE23 epitope is present in the intercellular space of both desmosomal and nondesmosomal areas. These results raise the possibility that there exist several biochemically closely related isoforms of desmoglein, one (AE23+/DG3.4+) restricted to epidermal desmosomes, one (AE23+/DG3.4-) uniformly distributed along the keratinocyte cell surface, and another (AE23-/DG3.4+) present in desmosomes of simple epithelia and basal cells of cultured keratinocytes. The uniform distribution of at least one desmoglein-related antigen in the intercellular space of keratinocytes coupled with the realization that different isoforms of desmogleins form a subfamily of cadherins suggest that desmoglein(s) may play a more general role in keratinocyte adhesion than previously appreciated.

Animals↗
PubMed1992

Simultaneous ectopic pregnancy with intra-uterine gestation after in vitro fertilization and embryo transfer.

A case of combined intra-uterine and tubal ectopic pregnancy is described following in vitro fertilization and the transfer of two four-cell and one two-cell embryos. This phenomenon is known to be related to ovarian stimulation by gonadotropin therapy, and there is an increased risk with tubal disease. Techniques applied at the time of embryo transfer, the use of culture medium with 50% fetal cord serum to convey the embryos to the uterus, the catheterization method, and the position of the patient during transfer are presented. The risk of multiple pregnancies and combined intra-uterine and ectopic gestations increases with numbers of transfers and large volume of transfer medium. We would therefore recommend that after IVF-ET treatment in women with tubal disease, intensive care should be taken in the early follow-up period to rule out the possibility of ectopic pregnancy. In this case, a viable ongoing intra-uterine pregnancy was confirmed after surgery for right ampullary ectopic pregnancy. And a 2,925 g male in excellent condition was delivered by Cesarean section without complications.

Adult↗
PubMed1992

Interaction of trichohyalin with intermediate filaments: three immunologically defined stages of trichohyalin maturation.

"Trichohyalin" is a 220-kD protein found in trichohyalin granules that are present as major differentiation products in the medulla and inner root sheath cells of human hair follicles. It was unclear whether this protein served as an intermediate filament precursor in the inner root sheath or as an intermediate-filament-associated (matrix) protein. We have produced a panel of monoclonal antibodies (AE15-17) to this protein and used them to trace its fate during inner root sheath differentiation. These studies have allowed us to define three immunologically distinct forms of this trichohyalin protein. They are 1) the AE15-positive form, which is found throughout all trichohyalin granules; 2) the AE16-positive form, which is localized as discrete punctae on the surface of trichohyalin granules; and 3) the AE17-positive, intermediate-filament-bound form, which associates with the inner root sheath filaments with a regular, 400-nm periodicity. From these results we suggest that the 220-kD trichohyalin protein is an intermediate-filament-associated protein that may play a role in the lateral aggregation, precise alignment, and stabilization of inner root sheath filament bundles.

Animals↗
PubMed1992

Expression of K12 keratin in alkali-burned rabbit corneas.

The healing of alkali-injured corneas is characterized by the persistence of polymorphonuclear leukocytes (PMN) in tissues and recurrent corneal epithelial defects. It has been suggested that the proteolytic enzymes secreted by PMN may account in part for the recurrent epithelial defects in the alkali-burned corneas. Cytoplasmic keratins, which form intracellular intermediate filaments, participate in the formation of hemidesmosomes and play a key role in the focal adhesion of epithelial cells to the basement membranes. The K3/K12 keratin pair is a major constituent of differentiated and stratified corneal epithelium. We have recently cloned the cDNA encoding the rabbit K12 keratin. In the present study we examined the expression of K12 keratin during the healing of alkali-burned rabbit corneas by slot-blot and in situ hybridization. Our results indicate that in normal cornea K12 keratin is equally expressed in all cell layers of stratified corneal epithelium and suprabasal layers of limbal epithelium, but not in bulbar conjunctival and other epithelia, i.e., lens, iris, and retinal pigment epithelium. The basal cells of the detached regenerating epithelium of the injured cornea express a very low level of K12 keratin. These observations are consistent with the notion that defective expression of K3/K12 keratins may play a role in the abnormal attachment of the regenerating epithelium to the basement membrane.

Animals↗
PubMed1992

Identification of an 85-100 kDa glycoprotein as a cell surface marker for an advanced stage of urothelial differentiation: association with the inter-plaque ('hinge') area.

Although bladder cancers account for almost 5% of all human cancer deaths, little is known about the biochemistry of urothelial differentiation. We have recently identified three major protein subunits ('uroplakins') of asymmetric unit membranes (AUM), which form rigid-looking plaques covering up to 70% of the apical surface of urothelial superficial (umbrella) cells. The ordinary-looking plasma membranes that interconnect these plaques are believed to be functionally specialized, serving as flexible but durable 'hinges'. Whether these hinge membranes are biochemically unique is unknown. Using a new monoclonal antibody (AE32) we have identified an 85-100 kDa glycoprotein (UGP85) which appears to be urothelium-specific. In both normal urothelium and cultured urothelial colonies this cell surface protein is associated mainly with superficial cells, suggesting that its expression is differentiation dependent. Results from in vitro translation experiments indicated that this glycoprotein contains a core polypeptide of about 55 kDa. Using immunogold localization techniques, we showed that in cultured urothelial colonies--which are known to lack mature AUM plaques--UGP85 is distributed relatively uniformly on the apical surface of some differentiated cells. However, in superficial cells of normal urothelium UGP85 is mainly associated with the hinge areas. These results raise the possibility that UGP85 is a plasma membrane component which can be excluded, to varying extents, from the plaque region as 12 nm protein particles are assembled into a tightly packed paracrystalline AUM structure. The identification of UGP85 provides the first evidence that the hinge areas interconnecting the urothelial plaques are biochemically distinguishable from the plasma membranes of the relatively undifferentiated urothelial cells of the lower cell layers.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Comparison of five bifunctional chelate techniques for 90Y-labeled monoclonal antibody CO17-1A.

Monoclonal antibody CO17-1A was radiolabeled with 90Y by five bifunctional chelate techniques. Radiation absorbed dose estimates for normal organs and tumor were calculated for each preparation based on timed tissue distribution studies in nude mice bearing SW 948 human colorectal carcinoma xenografts. The cyclic DTPA anhydride technique was inferior to the four other techniques studied. Data for SCN-Bz-DTPA and SCN-Bz-Mx-DTPA, which were conjugated to epsilon-lysyl amino groups, were similar to those for NH2-Bz-DTPA and NH2-Bz-Mx-DTPA, which were conjugated site specifically to oligosaccharides.

Animals↗
PubMed1991

Transient expression of mouse hair keratins in transfected HeLa cells: interactions between "hard" and "soft" keratins.

Although it has been shown previously that an acidic (type I) "soft" keratin can interact with many basic (type II) "soft" keratins to form 10-nm intermediate filaments, it has been unclear whether "soft" keratins are compatible with the "hard" keratins typically found in hair and nail. To address this issue and to generate more structural information about hard keratins, we have isolated and sequenced a cDNA clone that encodes a mouse hair basic keratin (b4). Our sequence data revealed new information regarding the structural conservation of hard keratins as a group, being significantly different from soft keratins. Using expression vectors containing appropriate cDNA inserts, we studied the expression of this basic (b4) as well as an acidic (a1) mouse hair keratin in HeLa cells. The expression of these alien hair keratins in the transfected cells was surveyed using a panel of monoclonal and polyclonal antibodies. Our results indicated that the basic and acidic hair keratin readily incorporated into the existing endogenous soft keratin network of HeLa cells. Overproduction of hair keratin, however, occasionally led to the formation of cytoplasmic aggregates containing both hard and soft keratins. These data suggest that although small amounts of newly synthesized hair keratins can incorporate into the "scaffolding" of the preformed soft keratin filament network, possibly through dynamic subunit exchange, overproduction of hard keratins can lead to the partial collapse of the soft keratin network. These observations, along with the deduced amino acid sequence data, support and extend the concept that hard and soft keratins, although closely related, are divergent enough to justify their being divided into two separate subgroups.

Animals↗
PubMed1991

Interaction of filaggrin with keratin filaments during advanced stages of normal human epidermal differentiation and in ichthyosis vulgaris.

Filaggrin is a histidine-rich, basic protein whose name was first proposed based on its ability to aggregate intermediate filaments in vitro. Based on this in vitro observation, it has generally been assumed that filaggrin functions in vivo as a matrix protein which causes keratin filaments to become densely packed in the terminally differentiated cornified cells. Inconsistent with this view however, is the well-known observation that keratin aggregation appears to proceed normally in the affected epidermis of ichthyosis vulgaris patients despite a greatly reduced quantity of filaggrin. To address this issue, we used immuno-electron microscopy to localize filaggrin and its cross-reactive precursor, profilaggrin, in human and mouse epidermis, as well as in ichthyosis vulgaris epidermis. We found that the localization of filaggrin in lower cornified cells correlates precisely with the formation of aggregated keratin filaments, and the disappearance of filaggrin in upper cornified cells correlates precisely with the loosening of keratin filaments. Furthermore, we showed that, even in ichthyosis vulgaris, small amounts of filaggrin/profilaggrin are present as electron-dense deposits associated with keratin filaments in the granular cells, and that the localization of this small amount of antigen again correlates with the aggregation state of keratin filaments. These data strongly suggest that filaggrin is indeed involved in filament aggregation in vivo.

Animals↗
PubMed1991

Regional heterogeneity in human corneal and limbal epithelia: an immunohistochemical evaluation.

The authors studied the distribution of specific keratins within the superior, inferior, medial, and lateral regions of human limbus and cornea to determine whether the limbal epithelium exhibits regional heterogeneity in its microstructure. A corneal epithelial basic keratin (K3), recognized by monoclonal antibody AE5, was immunohistochemically undetectable in the basal layers of the limbus in these four regions, but was seen in all layers in the central cornea. The pattern of immunostaining with another monoclonal antibody, AE1, which recognizes several acidic keratins, was complementary to AE5 staining in that AE1 recognized a similar heterogeneity in the limbal epithelial cells. AE1 immunoreacted with the basal cells of the limbus, but not those of the central corneal epithelium. Limbal characteristics, as defined by AE1-positive and AE5-negative staining, extended deeply into peripheral cornea in the superior and inferior regions, but to a lesser extent in the lateral and medial regions. The broader regions of epithelium with limbal characteristics in the superior and inferior regions raises the possibility that these regions play an important role in corneal epithelial maintenance and wound healing.

Aged↗
PubMed1991

Simultaneous ectopic pregnancy with intrauterine gestation after in vitro fertilization and embryo transfer.

A case of combined intrauterine and tubal ectopic pregnancy is described following in vitro fertilization and the transfer of two four-cell and one two-cell embryos. This phenomenon is known to be related to ovarian stimulation by gonadotropin therapy, and there is an increased risk with tubal disease. Techniques applied at the time of embryo transfer, the use of culture medium with 50% fetal cord serum to convey the embryos to the uterus, the catheterization method, and the position of the patient during transfer are presented. The risk of multiple pregnancies and combined intrauterine and ectopic gestations increases with increasing numbers of transfers and large volume of transfer medium. We would therefore recommend that after IVF-ET treatment in women with tubal disease, intensive care should be taken in the early follow-up period to rule out the possibility of ectopic pregnancy. In this case, a viable ongoing intrauterine pregnancy was confirmed after surgery for right ampullary ectopic pregnancy. And a 2925gm male in excellent condition was delivered by cesarean section without complications.

Adult↗